ARMY TM 9-2815-260-24P AIR FORCE TO 38G1-125-4 MARINE CORPS TM 09249A/2815-24P/4 vi Code Explanation AO -      (Assembled by org or unit) Items with these codes are not to be requested/requisitioned   AF -   (Assembled by DS or individually.   The parts that make up the assembled item must be intermediate) requisitioned or fabricated and assembled at the category of AH -      (Assembled by GS) maintenance indicated by the source code.  If the 3rd position code of AL -   (Assembled by SRA) the SMR authorizes you to replace the item, but the source code   AD -      (Assembled by Depot) indicates the item  is assembled at a higher category, order the item from the higher category of maintenance. Code Explanation XA -       Do not requisition an “XA”-coded item. order its next higher assembly. (Also, refer to the NOTE below.) XB - If an “XB” item is not available from salvage, order it using the FSCM and part number given. XC - Installation drawing, diagram, instruction sheet, field service drawing, that is identified by manufacturer's part number. XD - Item is not stocked.  Order an “XD”-coded item through normal supply channels using the FSCM and part number given, if no NSN is available. NOTE:  Cannibalization or controlled exchange, when authorized, may be used as a source   of supply f or items with the above source codes, except for those source coded “XA” or those aircraft support items restricted by requirements of AR 700-42. (2) Maintenance Code.  Maintenance codes tell you the category (s) of maintenance authorized to USE and REPAIR support items.  The maintenance codes are entered in the 3rd and 4th positions of the SMR Code as follows: (a)    The maintenance code entered in the 3rd position tells you the lowest maintenance category authorized to remove, replace, and use an item.  The maintenance code entered in the 3rd position will indicate authorization to one of the following categories of maintenance. Code    Application/Explanation C Crew or operator maintenance done within organization or unit maintenance. O Organizational or unit category can remove, replace, and use the item. F Direct support or intermediate category can remove, replace, and use the item. H General support catagory can remove, replace, and use the item. L Specialized repair activity can remove, replace, and use the item. D Depot catagory can remove, replace, and use the item.